There really aren't that many boarded (or really otherwise) behavior specialists out there. ...
Physiology and neurology specialities, or even devoted interest really isn't at all something that goes hand-in-hand with behavior the way you seemed to want to indicate.
I'm not sure about boards, but I do know that Cornell has a graduate field concentrating in behavioral physiology.
Here's the excerpt from
http://www.vet.cornell.edu/oge/physiology/concentrations.htm:
Behavioral Physiology
Houpt, Katherine A.
vertebrate social behavior, especially reproductive behavior; hormones and behavior; avian behavior; sex differences and their development; neuroethology of sexual behavior; comparative sexual behavior and reproductive biology
Place, Ned
mammalian reproductive biology, with a focus on the life history trade-offs associated with the timing of hormone secretion and reproductive effort. I have studied sexual differentiation and mating behavior of spotted hyenas under semi-natural conditions, the seasonal reproductive endocrinology of yellow-pine chipmunks in the field, and most recently, the effects of photoperiod on reproductive aging in Siberian hamsters. I strive to pursue basic research that is integrative and comparative, while also being biomedically and ecologically relevant.
Regan, Elizabeth Adkins
vertebrate social behavior, especially reproductive behavior; hormones and behavior; avian behavior; sex differences and their development; neuroethology of sexual behavior; comparative sexual behavior and reproductive biology
I'm also going to be taking a seminar next semester entitled Hormones and Behavior, which is an advanced physiology course - so physiology does jump to mind when I think behavior! I really have no idea what formal training there is for behavioral experts.
Also, is behavior the focus of the original poster? I'm still not sure what veterinary psychology is...